I'm a bit confused on how to use the ARC 2 Virtual Monitoring presets, as to me they all sound so different and make my mixes sound so different, that I just end up getting confused and frustrated. How are you all using these different presets? How do you make them useful? What are you listening for when you listen to your mixes through these different settings?

When I turn on "laptop speakers" and the bass disappears in what was once a nice full mix, it just reminds me of how futile mixing is and I become extremely depressed!

You can use them to double check your mixes on different systems. It models different playback mediums to double check the balance of the mix and how well it will transfer on less than systems that you may be monitoring on. Or in some of the presets, better than monitoring. ARC is all about helping your music translate better across multiple playback systems.

I understand the theory, but I guess I just dont understand how to apply it to my mixes.

Start small. Use ARC normally to correct your room and mix your song. After you are done, check the mix on some of the other presets to see how well it sounds on a lesser set of speakers.